BIOM20002 Lecture Notes - Lecture 33: Esophagus, Bioavailability, Intramuscular Injection
Document Summary
Deals with dose, absorption into blood, distribution to tissues, removal of drug (elimination) Things that you will be able to explain. Why thiopental has a half-life of about a day but is used as an ultra short-acting anaesthetic. How eating a meal slows the absorption of alcohol. Why (cid:373)oder(cid:374) a(cid:374)tihista(cid:373)i(cid:374)es do(cid:374)"t (cid:373)ake you dro(cid:449)sy (cid:271)ut old o(cid:374)es do. Why thyroxine can be taken once a week but penicillin has to be taken 4 or more times a day. Drug binds to receptors, some bound to tissues, some bound to proteins in blood and tissues. All routes of drug delivery require absorption across barriers, except injection into the blood (and applying drug straight onto affected site) Oral (patient-preferred): easy, non-invasive entry into portal circulation from git, potential first pass metabolism in liver (could inactivate majority of dose), before reaching systemic circulation. Sublingual: drug administered orally but is not swallowed, but held under tongue.